Accession Number : ADA294307

Title :   Anemometer Design Using the Aerodynamic Drag of Circular Cylinders with Vortex Controlling Surface Protrusions.

Corporate Author : NAVAL AIR WARFARE CENTER AIRCRAFT DIV WARMINSTER PA

Personal Author(s) : Lake, Robert E.

PDF Url : ADA294307

Report Date : 09 MAY 1995

Pagination or Media Count : 22

Abstract : A series of wind tunnel and flight tests were conducted to determine the ability of four anemometer configurations to accurately measure helicopter rotor downwash outflow magnitude and direction. The anemometers were designed to use the aerodynamic drag produced on a circular cylinder as the sensing stimulus. The non-linearities in drag with respect to Reynolds numbers that are associated with smooth cylinder flow were overcome by incorporating vortex controlling surface protrusions. The four surface protrusion configurations discussed here include vertical flutes, helical strakes, and small and large grid mesh. Measurement performance was quantified by determining the sensor's range, calibration accuracy, linearity, frequency response, accuracy in measuring angle of wind incidence, and ability to correct angle of attack induced errors. Testing demonstrated that the four configurations show comparable downwash measuring performance to the ion beam deflection anemometer. Although the sensor's design was intended for measuring helicopter rotor downwash, the results from this paper can be applied to a variety of high velocity measurement applications as well.

Descriptors :   *AERODYNAMIC DRAG, *ANEMOMETERS, ANGLES, FLIGHT TESTING, MEASUREMENT, DETECTORS, HIGH VELOCITY, ATTACK, GRIDS, WIND, DEFLECTION, ACCURACY, ION BEAMS, HELICOPTER ROTORS, ROTOR BLADES(ROTARY WINGS), MESH, SURFACES, CYLINDRICAL BODIES, ERRORS, CALIBRATION, FLOW, DRAG, ROTORS, WIND TUNNELS, REYNOLDS NUMBER, DOWNWASH, FREQUENCY RESPONSE, STRAKES, CIRCULAR, HELIXES.

Subject Categories : Aerodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE